Friedmann effective potential for pressureless matter
= Friedmann effective potential for pressureless matter
{c}
{title2=$V(a)=-\mu/a-\Lambda a^2/3$}
For pressureless matter normalized by $\rho=3\mu/(8\pi a^3)$ in units $G=c=1$, the <Friedmann equation> is
$$
\dot a^2+V(a)=-k,
\qquad
V(a)=-\frac{\mu}{a}-\frac{\Lambda a^2}{3}.
$$
Allowed scale factors satisfy $V(a)\leq-k$, and equality marks a <turning point>.